I flew AA107 yesterday in the 77W in J, and had time when I boarded to get a good look at MCE and PE.
MCE:
Row 20 bulkhead. The bulkhead is just a partition, and has a decent gap at floor level, meaning tall people have extra foot room. (photo post 776)
Row 31 exit row. Like row 31 on all 777s, endless leg room but the door protrusion. (photos post 773)
Row 32. Window/aisle pairs, definitely do have extra leg room.
Row 33 centre block bulkhead. This a proper bulkhead so no extra foot room.
Row 34 and 35 centre block. I was able to confirm these two part-rows do indeed have extra legroom. This hadn't been explicitly confirmed here, I believe. How they've done it is not clear.
PE: (first time I've actually seen the PE seats)
Row 16 exit window pairs, endless leg room, centre block bulkhead, quite decent legroom but it is a full bulkhead.
Row 17, 18, 19. My wife flew in the centre block of these rows a couple of times and her main comment is the poor spacing of the seat supports for the row in front. I assume they had to make the seat rows fit the floor which was originally set up for 3-3-3 Y, but it leaves the seat supports right where you want to put your feet.